Pathologist Offers More Best-Practice Tips, Part 4

We wrap up our conversation with pathologist Ken Mero by debunking a few myths and preventing a few frustrating situations.

By Phil Zeltzman, DVM, Dipl. ACVS

Published: 2012.04.06 02:33 PM

Myxofibrosarcoma near a 13-year-old cat’s foot pads

Courtesy of Dr. Phil Zeltzman

We wrap up our conversation with pathologist Ken Mero, BS, MS, DVM, Ph.D., of VetPath Services in Stone Ridge, N.Y., by debunking a few myths and preventing a few frustrating situations.

How can veterinary practices avoid losing biopsy samples?
Few things in life are as frustrating for the practitioner and the pet owner as a lost sample. These suggestions may seem obvious, but make sure:

1. The formalin container is labeled with the client’s and pet’s names as well as the anatomical site of origin.
2. The formalin container lid is tightly closed.
3. The laboratory’s address is on a separate piece of paper inside the shipping box in case the outside label is destroyed.
4. You request cassettes and sponges for small endoscopic specimens so they don’t fragment into tiny particles too small to recover from the formalin container.
5. You use plastic rather than glass containers for shipment. Plastic containers are less likely to break in transit.
6. If your specimen is especially large, save part of it at your practice in case more tissue is needed by the pathologist. This is especially true for large splenic masses.

What are the top 10 mistakes made when samples are sent?
From experience, I’d say:

1. No clinical history.
2. Too much clinical history. For example, multiple copies of the clinical record that go back to infancy.
3. No patient ID on the formalin jar.
4. No specimen information on the test request form.
5. No indication of the nature of the biopsy: incisional, excisional, etc. (See Part 1 in the June 2011 issue of Veterinary Practice News.)
6. Writing the wrong patient ID or species, or the wrong client name.
7. Putting samples from different patients in the same formalin jar. (Yes, it happens.)
8. Biopsies sent in saline rather than formalin.
9. Biopsies so small that they don’t survive processing.
10. Requesting margin evaluation on a partially excised or submitted sample.

Can you debunk a few urban legends and myths?
Sure. I’ll share a few:

1. You can stick a needle in anything and get an instant diagnosis.
2. All biopsy specimens, of any size and type, can be processed overnight.
3. One size formalin jar fits all.
4. A pathology lab is a “body shop and parts department.”
5. A cytological diagnosis can be made on two cells.
6. Pathology is a cut-and-dry science (pun intended).
7. A lab can generate a report “yesterday.”
8. Nothing ever goes wrong with lab equipment.
9. Our dictation software never makes mistakes.
10. Pathologists are psychopathic misfits who could not make it one day in practice.

What are your biggest pet peeves?
I may repeat myself, but here are a few annoyances:

1. No clinical history or specimen source.
2. Illegible writing on the test request form.
3. Cytologic preparations so thick they look like tissue.
4. Cytologic preparations with no cells, or with all cells crushed or smudged.

5. Biopsy specimens so tiny that they do not maintain any integrity after processing.
6. Biopsies of inflammatory skin disease submitted after having been blasted with antibiotics or steroids.
7. Submitting a toenail to determine why it fell off.
8. Biopsy specimens that seem to have been squeezed with vice grips, so tissues end up compressed and cells ruptured.
9. Biopsy specimens that have been cooked by electrocautery or laser excision
10. Autolyzed tissues from postmortem or frozen specimens.

Is it true that pathologists rarely commit themselves when reading an FNA sample—with the exception of obviously diagnostic lesions—and give out multiple ruleouts instead?

A realistic way to consider cytology is as an indicator as how to proceed next: immedia ate treatment, biopsy, etc. The use of cytology in some cases is to help with general classification of a lesion: inflammatory vs. neoplastic. Especially with neoplasia, the diagnosis may be no more specific than “epithelial or mesenchymal or round cell tumor.” The cytological distinction of benign vs. malignant status may not be clear with cytology alone.

Within each broad category of neoplasia are many differential diagnostic possibilities. Therefore, the pathologist may offer the most likely differential possibilities rather than commit himself to a specific diagnosis, which would be an unjustified overspeculation.

This may be considered a diagnostic noncommitment to the practitioner, but it is a diagnosis based on the aspirate. Some aspirates are completely nondiagnostic, but the pathologist may attempt to be helpful by offering some noncommittal suggestions based on clinical signs and history.

Should every wart or fatty tumor be read by a pathologist?

It is wise for lesions to be assessed histopathologically. Some masses are not actually what they appear to be. Warts may indeed be merely a focus of fibroepithelial hyperplasia, but they also may conceal an underlying lesion such as a sebaceous tumor or a melanoma.

Some lesions are excised based upon a prior cytologic determination and justify a histopathological confirmation. A fatty mass may be merely an accentuated fat pad, a simple lipoma, an infiltrative lipoma or liposarcoma. Histopathology is helpful for the final diagnosis based on the lesional periphery: benign, well-defined, circumscribed, malignant or locally invasive.

Liposarcomas may appear similar to benign or infiltrative lipomas depending on their stage of differentiation. Also, some tumors such as nerve sheath tumors, myxofibromas and myxofibrosarcomas have a fatty appearance that may mimic a lipoma. But their histogenesis and behavior are clearly very different.

Another benefit of histologic assessment of lesions is your liability. Some grossly quiescent-appearing lesions recur with a vengeance. A nonconfirmed presumptive diagnosis or prognosis subsequently proven incorrect by future clinical events may be the subject of litigation.

If money is really tight and lesions are not submitted, they could be saved at the clinic and sent to the lab later, especially if the lesion recurs.

This article is the fourth part of a series. The other parts are located here: Part 1, Part 2, Part 3.